Process for making peroxymonosulphuric acid



SULPHURIC ACID Eric T.-Fell, Ambergate, England, assignor to Stevensons '(Dyers) Limited, Ambergate, England, a corporation of Great Britain No Drawing. Application December 14, 1953, Serial No. 398,195

4 Claims, 01. 252-186 This invention relates to a process for-making peroxymonosulphuric acid and products produced thereby.

Peroxymonosulphuric acid has been heretofore known experimentally, but, so far as I am aware, no practical use has been made of it until that described in my co' pending applications Ser. No. 228,143, filed May 24, 1951, now Patent 2,701,178, and Scr. No. 282,902, filed April 17, 1952, now Patent 2,739,034. Each of these applications relates to the treatment of wool by mixtures containing such acid to render it shrink-resistant. Practical operation of these processes and, in general, commercial use of the acid requires that it be sufficiently stable to be shipped and handled. The term peroxymonosulphuric acid refers to the same substance as the term permonosulphuric acid, which latter term appearsin' said Patents 2,701,178 and 2,739,034. 1

-The principal object .of the present invention accordingly is to provide a simple eflicient processfor the manufacture of peroxymonosulphuric acid and compositions containing same, and to produce a product which may be shipped and handled commercially.

The invention accordingly comprises the novel products as well as the novel processes and steps of processes according to which such products are manufactured, the specific embodiments of which are described hereinafter by way of example and in accordance with whichI'now prefer to practice the invention. e

I have found, inaccordance with my invention, that regulated amounts of concentrated sulphuric acid and hydrogen peroxide may be flowed together to produce a mixture of peroxymonosulphuric acid, sulphuric acid and water, and that the mixture should be cooled quickly as it flows to inhibit substantially further reaction. The cooled flowing mixture is then diluted with cool water to produce a solution which may be employed practically. .I have-foundthat the solutionrnentioned will have a stability so that it may be shipped and, handled for use in various commercial processes. Thus, such solutions may be used, for example, but without limitation, in the processes of the invention of my applications referred to bo ,J

In carrying'out my processghy drogen peroxide is mixed with anequalamount, 'or'larger amount, of sulphuric acid containing at least 88% ('sp. gr. 1.7) of H2SO4 by weight.

Hydrogen peroxide solutions of varying concentrations may be employed as reactants. Where solutions ofaqueous hydrogen peroxide of less concentration than 50% by weight are employed, the reaction, time is substantially instantaneous, producing a corresponding rise i i-temperature and the cooling zone may be situated substantially at the point of mixingl In general a flow of one volume of hydrogen peroxide to three orv four volumes of.su1phuric acid (sp. gr. 1.84) is satisfactory to give a high conversion of hydrogen peroxide into peroxymonosulphuric acid. The conversion is incomplete andthereis always asmall amount-of hydrogen peroxide in the diluted product as formed.

Where smaller proportions of sulphuric acid are used nitf S ws Patmt to e table occurring when the peroxide volume exceeds that of sulphuric acid.

ABLE Unit volume flow per sec. Conversion of H903 into peroxymono- Sulphuric acid, 90% H 0 sulphuric acid,

Sp. Gr. 1.84; I percent The concentration of sulphuric acid used is critical.

' Thus, solutions of sulphuric acid less than 88% by weight perature.

(sp. gr. 1.7) do not give a satisfactory conversion of hydrogen peroxide into peroxymonosulphuric acid where the stream of reactants prior to mixing are at room tem- The process is conveniently carried out in a continuous manner by running together a stream of hydrogen peroxide at a substantially uniform velocity and a stream of concentrated sulphuric acid at a substantially uniform velocity. As indicated above, the volume of the streams may be equal but the volume of the concentrated H2SO4 stream is preferably larger than that of the hydrogen peroxide. An exothermic reaction takes place and the flow should be regulated so that the temperature of the mix: ture rises quickly to at least about 50 C. The rate of flow is such that this temperature exists preferably for several seconds and the flowingmixturethen enters the cooling zone where it is preferably cooled to room tem-' perature. Prolonged contact of the concentrated sulphuric acid and hydrogen peroxide mentioned in the proportions indicated beyond the point where the maximum yield of peroxymonosulphuric acid is produced will result in a loss of oxygen and corresponding reduction in the yield of peroxymonosulphuric acid. In general the rise of temperature is instantaneous and the chemical conversion takes place almost immediately. Accordingly, as stated, the reactingtime prior to cooling occupies only several seconds. t

Substantially immediate dilution is important because of the instabilityand hazardous character of the product in the undiluted form. Thus, a product formed of 47% sulphuric acid, 43% peroxymonosulphuricacid and 5% water and 5% hydrogen peroxide is hazardous because it will cause fires in combustible materials. Thus, if cotton or 'wool is brought in contact with such solution, it will ignite and burn. Stable compositions which may be used in practice I have found should contain from an appreciable amount to about 15 parts of peroxymonosulphuric acid, from an appreciable amount to about 15 parts of hydrogen peroxide, from an appreciable amount to about useful for various other purposes.

The method of dilution-"we have found to be themost Patented Apr. 23,

practical is to pump the correct proportion of water to peroxide and sulphuric acid used into the weer pdr'ti'oii of the cooling system beyond the zone in which the peroxymonosulphuric acid is formed so that the dilutedv peroxymonosulphuric acid issues". from the system. According to another embodiment" of thc. invention two coolmg systems in series are provided, the net being used for cooling the mixture and the second for dilution of this mixture.

The following are examples of the reeess'as' i new prefer to practice it. It is to be understand. that these examples are illustrative and the invention is notv to be. considered as" restricted thereto; exce t as": indicated in the appended claims.

Unless otherwise indicated all pfdportidns are by weight. 7

Example 1 Streams at room temperature of concentrated sulphuric acid (sp. gr. 1.84") 'and'50%- by weight aqueous hydrogen peroxide were flowed together at 20' and 73 volumes per minute respectively. The mixingtook place at the mouth of a water-cooled condenser. As it flowed through the condenser the mixture had a reaction time of one second before cooling to about 15 C. The temperature of the water used for cooling was 15 C.

The cooled mixture which: issued from this condenser was then mixed with a stream of water at about 15 C. flowing at the rate of 160 volumes per minute and flowed a: second water-cooled condenser'using water at about The solution flowing from the second condenser co'ntamed approximately 6% by weight of peroxymonosulphuric acid, 81.5% water, 12.0% sulphuric acid and 0.5% by weight of unconverted hydrogen peroxide'an'd was sufficiently stable for commercial requirements. The content of peroxyr'nonosulphuri'c' acid was substantially unchanged on storage for 30 days and the conversion was over 80% of the peroxide used witha' yield of 80%. The stability of this solution was two weeks.

The stability test for this example and the succeeding examples was made by titration of the solution to determine its content of peroxy'rnonosulphuric acid. when an appreciable change, viz. a decrease of 20% in the peroxymo'nosulphuric acid content, was noted in the con tent, the period at which that change commenced was given as the stability period.

Example 2 Streams at room temperature of concentrated sulphuric acid' (sp. gr. 1.84) and 35% by weight aqueous hydrogen peroxide were flowed together at 20 and 6.8 volumesper minute respectively.

The flow of both chemicals was so arranged that the commingling took place well within the cooling zone of a condenser jacketed with running water at approximately 10 C. Cooling was substantially immediate after mixing.

The cooled mixture, which. issuedfr'om -'the condenser was then led into a tank containingwater at. approximately 10 C. which was kept cool by ice.- This dilution was effected by taking 2,000 volumes of. water for every 200 volumes of sulphuric acid originally taken,

The diluted solution so obtained approximately 2.8% by weight of peroxymonosulphuric acid, 84% water, 13% sulphuric acid and 0.2% by Weight of hydrogen peroxide and was quite stablev for commercial, purposes. The con version was over 80% of the peroxide used. The yield was about 80%. The stability of this solution was three weeks.

Example 3' Streams at room temperature of concentrated sulphuric. acid (sp. gr.- 1.84) and 9.0% by; weight aqueous H202 were flowed together at. 20- and 7.3; volumes perminuterespcctively. The mixing tookplace at the mouth of d a water-cooled condenser, with the water being at 15 C., which was so arranged that the mixture had a re' action time of about 2 seconds before cooling.

The cooled mixture issuing from the condenser was then led into a tank of water at approximately 10 C., which was kept cool by ice.- This dilution was eifectcd by taking 3,000 volumes of water for every 200 volumes of sulphuric acidoriginally taken.

The diluted solution so obtained contained approximately 7% by weight of peroxymonosulphuric acid, 87.6% Water, 4.8% sulphuricacid, and 0.6%by weight of hydrogen peroxide and was quite stable for commercial purposes. The conversion was over of the peroxide used. The yield was about 80%. The stability of this solution was six weeks.

Example 4 Concentrated sulphuric acid, sp. gr. 1.84, and by weight hydrogen peroxide were flowed together at 20 and 12 volumes respectively into the mouth of a water cooled condenser, at such a point that the mixture had a reaction time of approximately three seconds before entering-the cooling zone. a

The cooled mixture was. then flowed together with volumes of water at a temperature of 10' C. and keptcool by an ice jacket.

The diluted solution so obtained contained approximately 15 peroxymonosulphuric acid and was stable for 4 days.

Chemical analysis showed that over 70% of the hydrogen peroxide originally taken had been converted into peroxymonosulphuric acid. The yield was about 70%.

Example 5 streams at room temperature of concentrated sulphuric acid' (sp. gr. 1.84) and 90% by' weight hydrogen peroxide were flowed. together at 20 and 12 volumes respectively into the mouth of a water cooled condenser, cooled at 10 C., at a point such that the mixture had a reaction time of approximately'thre seconds before entering the cooling zone. v I

The cooled mixture was then led into 200 volumes of water at a temperature of 10 C. kept coolby an ice jacket. 7

The diluted solution so obtained containedapproximately 12.0% of peroxymonosulph'uri'c acid, 82.3% water, 4.6% sulphuric acid and 1.1% hydrogen peroxide. It was stable for 30 days. The yield wasabove 80%.

The water employed in the above examples is a good quality of soft water. Hard water and water containing large amounts of impurities would give a less stable product.

What I claim is:

1. A process which consists in, flowing together regulated amounts of concentrated sulphuric acid containing not less than about 88% of said acid and hydrogen peroxide under reaction temperature to produce 'peroxymonosulphuric acid, sulphuric acid, water and hyd'r'ogen'peroxide, cooling the resulting; mixture several secondsafic'r such reaction to inhibit substantially further reaction and diluting theflowingmixture with water to produce a solution containing not more than 15% peroxymonosulphuric acid.

2. A process which consists in, bringing. together re'gw lated streams of concentrated sulphuric acid containing oxide under reaction conditions to produce peroxymonc sulphuric acid, sulphuric acid, water and hydrogen peroxide, rapidly cooling the resulting mixture to room temperature then as it flows to inhibit substantially further reaction and diluting the flowing mixture with water to produce a solution containing not more than 15% per oxymonosulphuric acid.

4. A process which consists in, bringing together regu lated streams of concentrated sulphuric acid containing not less than about 88% of said acid and hydrogen peroxide in proportions such that the sulphuric acid is in the proportion of a unit volume flow per second of about 10 volumes of sulphuric acid to about 4 volumes of 90% References Cited in the file of this patent UNITED STATES PATENTS Greenspan Dec. 22, 1953 OTHER REFERENCES Systematic Inorganic Chemistry, Yost and Russell, Prentice-Hall Inc., 1944, N. Y., page 372. 

1. A PROCESS WHICH CONSISTS IN, FLOWING TOGETHER REGUNATED AMOUNTS OF CONCENTRATED SULPHURIC ACID CONTAINING NOT LESS THAN ABOUT 88% OF SAID ACID AND HYDROGEN PEROXIDE UNDER REACTION TEMPERATURE TO PRODUCE PEROXYMONOSULPHURIC ACID, SULPHURIC ACID, WATER AND HYDROGEN PEROXIDE, COOLING THE RESULTING MIXTURE SEVERAL SECONDS AFTER SUCH REACTION TO INHIBIT SUBSTANTIALLY FURTHER REACTION AND DILUTING THE FLOWING MIXTURE WITH WATER TO PRODUCE A SOLUTION CONTAINING NOT MORE THAN 15% PEROXYMONOSULPHURIC ACID. 